Flow control valve

Abstract

A flow control valve having a bypass valve section that opens when a main valve section has approached a closed state has a bypass start point that can be easily varied and adjusted, even after installation of the flow control valve. Further, cavitation is not generated in the valve. The flow control valve comprises a cylindrical body having a bypass valve seat and a plurality of protrusions on an inner peripheral surface to form bypass flow passages therebetween. A bypass opening and closing body has a bypass valve element formed at its front end portion and a plurality of slit holes formed on its outer peripheral surface so as to open and close the bypass flow passages between the respective protrusions, and is disposed in an axially movable manner. A piston is disposed in an axially movable manner in the bypass opening and closing body and has an enlarged outer diameter section formed on its rear portion and a communication hole penetrating therethrough in the axial direction. An adjusting member has a rear end portion of the piston fitted therein and is formed in such a manner that a resistance may be applied to the flow of fluid into a control chamber depending upon a fitting depth of the piston. An adjusting bolt variably sets the position of the adjusting member in the axial direction.

What is claimed is: 
     
       1. A flow control valve comprising: a valve housing having a main valve section comprising an inlet, an outlet, a main valve seat between said inlet and said outlet and a main valve element engageable with said main valve seat, and a bypass valve section;   a cylindrical body in said bypass valve section, said cylindrical body having an inner peripheral surface, a bypass valve seat thereon and a plurality of protrusions on said inner peripheral surface forming bypass flow passages therebetween;   a bypass opening and closing body disposed in an axially movable manner in said cylindrical body, said bypass opening and closing body having an outer peripheral surface, a first portion, a bypass valve element on said first portion adapted to butt against said bypass valve seat, a plurality of holes on said outer peripheral surface for opening and closing said bypass flow passages between said protrusions on said inner peripheral surface of said cylindrical body simultaneously with opening and closing of said bypass valve element, and a second portion having an enlarged outer diameter section in contact with said inner peripheral surface of said cylindrical body;   a piston disposed in said bypass opening and closing body in an axially movable manner and extending through said bypass opening and closing body, said piston having a rear portion with an enlarged outer diameter section and a communication hole extending axially through said piston;   a control chamber defined in said bypass valve section adjacent to said second portion of said bypass opening and closing body;   an adjusting means for receiving said rear portion of said piston and applying a resistance force to the flow of fluid between said communication hole in said piston and said control chamber in dependence upon the depth of penetration of said rear portion of said piston therein; and   an adjustment setting means accessible from outside of said valve housing for variably setting an axial position of said adjusting means.   
     
     
       2. The flow control valve of claim 1, wherein said bypass opening and closing body has a collar thereon forming said holes. 
     
     
       3. The flow control valve of claim 1, and further comprising an adjustable stopper in said bypass valve section for adjustably setting a full open position of said bypass opening and closing body. 
     
     
       4. The flow control valve of claim 1, wherein said adjusting means comprise a member mounted in said bypass valve section adjacent to said second portion of said bypass opening and closing body, said member having an interior space receiving said rear portion of said piston with a fluid channel extending between said rear portion and said member so as to fluidly communicate said interior space with said control space. 
     
     
       5. A flow control valve comprising: a valve housing comprising a main valve section comprising an inlet, an outlet, a main valve seat between said inlet and said outlet and a main valve element engageable with said main valve seat, and a bypass valve section having a bypass outlet;   a cylindrical body fixed in said bypass valve section, said cylindrical body having an inner peripheral surface, a bypass valve seat thereon between said main valve and said bypass outlet, and a plurality of protrusions on said inner peripheral surface forming bypass flow passages therebetween, said bypass outlet being in communication with one of said bypass flow passages;   a bypass opening and closing body disposed in an axially movable manner in said cylindrical body, said bypass opening and closing body having an outer peripheral surface slidable against said protrusions of said cylindrical body, a front end portion, a bypass valve element on said front end portion adapted to butt against said bypass valve seat, a plurality of holes in said outer peripheral surface, a rear end portion having an enlarged outer diameter section in slidable contact with said inner peripheral surface of said cylindrical body, and an interior peripheral surface;   a first fluid channel defined by said cylindrical body and said bypass opening and closing body communicating said interior peripheral surface of said bypass opening and closing body with said bypass outlet;   a piston disposed in said bypass opening and closing body in an axially movable manner and extending through said bypass opening and closing body, said piston having a rear portion with an enlarged outer diameter section in slidable contact with said interior peripheral surface of said bypass opening and closing body and a communication hole extending axially through said piston;   a control chamber defined in said bypass valve section adjacent to said rear end portion of said bypass opening and closing body;   a second fluid channel defined between said rear portion of said piston and said interior peripheral surface of said bypass opening and closing body communicating said control chamber with said first fluid channel;   an adjusting member mounted in said bypass valve section having an interior receiving said rear portion of said piston wherein said communication hole in said piston communicates said interior of said adjusting member with said main valve section;   a third fluid channel communicating said interior of said adjusting member with said control chamber; and   an adjustment member extending from outside of said valve housing into said bypass valve section into contact with said adjusting member for axial adjustment of the position thereof.   
     
     
       6. The flow control valve of claim 5, wherein said rear portion of said piston and said interior peripheral surface of said bypass opening and closing body have a variable contact length variable by movement of said piston relative to said bypass opening and closing body for varying the fluid resistance of said second fluid channel. 
     
     
       7. The flow control valve of claim 5, wherein said rear portion of said piston and said interior of said adjusting member have a variable contact length variable by movement of said piston relative to said adjusting member for varying the fluid resistance of said third fluid channel. 
     
     
       8. The flow control valve of claim 5, and further comprising an adjustable stopper in said bypass valve section for adjustably setting a full open position of said bypass opening and closing body.